A light emitting diode (LED) is a device including an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed between the n- and p-type semiconductor layers. When a forward electric field is applied to the n- and p-type semiconductor layers, electrons and holes may be injected into the active layer and recombine in the active layer to emit light.
An LED module including a plurality of LEDs is disclosed in, for example, U.S. Patent Publication No. 2011-0127568. The surface-mount LED module includes a p-type pad and an n-type pad formed on a top surface of an LED. However, since the p-type pad is electrically connected to the entire surface of p-GaN exposed by an insulating layer, current crowding may occur.
In addition, depending on the type of a chip, an LED may include a reflection layer. For example, the type of a flip-chip is characterized by emitting light through a substrate. Accordingly, after a semiconductor layer is formed on the substrate, a reflection layer formed of a metal is introduced on the semiconductor layer or a current spreading layer, and light is reflected by the reflection layer. Also, a barrier layer is provided on the reflection layer. The barrier layer is provided to prevent diffusion of the metal forming the reflection layer.